Hydroisomerization and hydrocracking of n-heptane on Pth zeolites. Effect of the porosity and of the distribution of metallic and acid sites.

Guisnet, M.; Álvarez, F.; Giannetto, G.; Pérot, G.

doi:10.1016/0920-5861(87)80007-x

Cited by 212 publications

(118 citation statements)

References 10 publications

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“…It occurs when there are multiple transformations at acid sites inside pores that significantly limit sorbate mobility (14,28,38,40). This happens when the hydrogenation function is insufficiently active as compared to the acid function (38,(41)(42)(43) or when the mass transport between the hydrogenating sites and the acid sites is the rate-limiting step (18,38,41,43).…”

Section: Resultsmentioning

confidence: 99%

“…As the thermodynamic adsorption data relate to the shape selective properties that are intrinsic to a zeolite structure, we develop a criterion to identify catalytic data that are unimpaired by mass transport or hydrogenation rate limitations. A subsequent scrutiny of the published n-C 7 (8,18) and n-C 10 (5,(19)(20)(21)(22)(23) hydroconversion data using this criterion shows intrinsic differences in paraffin hydroconversion between MFI-and MEL-type zeolites. Simulated C 10 adsorption data are then used to explain the observed differences in the hydroconversion of n-C 10 and of complex feedstocks and the absence of such differences in a publication (8) on the hydroconversion of n-C 7 .…”

Section: Fig 1 Sketch Of the Mfi-(a)mentioning

confidence: 99%

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Differences between MFI- and MEL-Type Zeolites in Paraffin Hydrocracking

Maesen¹,

Schenk

Vlugt

et al. 2001

Journal of Catalysis

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A critical evaluation of published paraffin hydroconversion data shows that MEL-type zeolites preferentially hydrocrack paraffins where two methyl groups are separated by a methylene group, whereas MFI-type zeolites prefer paraffins with geminal methyl groups (preferably at the central carbon atom). Due to this difference in hydrocracking pathway, MEL-type zeolites will hydroisomerize a higher percentage of the feed than MFI-type zeolites at low temperature, while the reverse is true at high temperature. The free energies of adsorption calculated by means of configurational bias Monte Carlo (CBMC) molecular simulations are used to explain these differences in selectivity. They show that the MEL-and MFI-type zeolites favor the formation and hydrocracking of the dimethyl paraffins that have a shape commensurate with that of their pores. They indicate that the higher paraffin hydroisomerization selectivity of the MEL-type zeolites can also be explained by their higher selectivity for adsorbing linear rather than branched paraffins at high paraffin loading. At low paraffin loading this difference in adsorption selectivity disappears. Both temperature and loading effects could resolve a disparity in the literature between n-decane and n-heptane hydroisomerization selectivity data.

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Section: Resultsmentioning

confidence: 99%

Section: Fig 1 Sketch Of the Mfi-(a)mentioning

confidence: 99%

Differences between MFI- and MEL-Type Zeolites in Paraffin Hydrocracking

Maesen¹,

Schenk

Vlugt

et al. 2001

Journal of Catalysis

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“…It is well known that the final conversion and selectivity depend on a number of parameters including the acidity and pore structure of the zeolite, the nature and dispersion of the supported metal, and operating conditions such as temperature and contact time [7,[19][20][21]. The maximum isomer yield is reached when the metal and acidic functions of the catalyst are well balanced [22]. The nature of the metal clearly affects the final product distribution, which can be understood in terms of the type of mechanisms involved in the reaction.…”

Section: Introductionmentioning

confidence: 99%

Effect of the impregnation order on the nature of metal particles of bi-functional Pt/Pd-supported zeolite Beta materials and on their catalytic activity for the hydroisomerization of alkanes

Roldán

Beale²,

Sánchez‐Sánchez

et al. 2008

Journal of Catalysis

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A series of mono-and bi-metallic (Pt and/or Pd) impregnated zeolite Beta samples have been prepared, characterized using a number of experimental techniques and catalytically tested for the hydroisomerization of a mixture of light paraffins. In particular, the effect of the order of Pt and Pd impregnation on the type/structure of the metallic species of the zeolite support and on the catalytic activity has been studied. Studied samples included a zeolite Beta in which both Pt and Pd (0.5 wt% of each) were simultaneously impregnated (and subsequently calcined and reduced) and two equally metal-loaded samples where the metals were sequentially impregnated (samples Pt*-Pd/Beta and Pd*-Pt/Beta, in which Pt and Pd were impregnated first, respectively). Mono-metallic samples were also prepared for comparison. TPR, DR-UV-visible, TEM, and XAS studies confirm that the order of impregnation plays a key role in the formation of metallic particles, influencing aspects as decisive in their catalytic behavior as their size, their dispersion and their composition (e.g., mono-or bi-metallic). The initial impregnation of Pd and subsequently of Pt produces a higher number of hetero-metallic (Pt-Pd) bonds than the simultaneous co-impregnation and especially for the impregnation in reverse order, which does not produce Pt-Pd bonds in a detectable amount. Based on the results from the different characterization techniques, a model of the metal distribution and composition of the particles was proposed for each bi-metallic sample. In good agreement, the order of the catalytic activity was found to be Pd*-Pt/Beta > Pd-Pt/Beta > Pt/Beta > Pt*-Pd/Beta > Pd/Beta, making clear that not only the presence of both metals, but also an adequate preparation method generating a high number of hetero-metallic bonds must be taken into account to improve the catalytic properties in relation to the mono-metallic samples.

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“…In the present study, as the dpulse value increased to 4.2 nm, the ratio of Pt atoms comprising plane without edge and corner, which are active for hydrogenation/dehydrogenation, increased, resulting in the observed increase in the YC9-C15 and YC1-C8. A reaction scheme has been proposed based on the ratio of nPt to nA [12][13][14]. Figure 7b shows the effect of the nPt/nA ratio on the product yield based on the data in Table 4.…”

Section: Hydrocracking Behaviors Of Pt-loaded Zeolite Catalystsmentioning

confidence: 99%

“…As metal sites, not only precious metals such as Pt [8][9][10][11][12][13][14] and Pd [15], but also transition metals such as Ni [16], Ni-Mo [17], Co-Mo [18], Ni-W [19] have been reported. As solid acid catalysts, zeolite [10,12,13,16], amorphous silica-alumina [17,19], and alumina [15,18] have been investigated. Among bifunctional catalysts for hydrocracking of n-alkanes, which are main components of the FT product, Pt-loaded β-type zeolite catalysts exhibited higher product yields under mild conditions [8,10].…”

Section: Introductionmentioning

confidence: 99%

Preparation for Pt-Loaded Zeolite Catalysts Using w/o Microemulsion and Their Hydrocracking Behaviors on Fischer-Tropsch Product

et al. 2015

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Pt-loaded β-type zeolite catalysts with constant Pt content (0.11 wt.%) and similar pore structure were prepared using a water-in-oil (w/o) microemulsion. The effect of Pt particle synthesis conditions using microemulsion (a type of Pt complex-forming agents and the molar ratio of complex-forming agent to Pt 4+ ) on loaded Pt particle size was investigated. The Pt particle size of the Pt catalyst using tetraethylammonium chloride (TEAC) as a complex-forming agent with the molar TEAC/Pt ratio 10 was the minimum value (3.8 nm), and was much smaller than that (6.7 nm) prepared by the impregnation method. The utilization of the complex-forming agent of which hydrophobic groups occupied a small volume and the appropriate complex-forming agent/Pt ratio were favorable for synthesis of small Pt particles. The effect of loaded Pt particle size on the hydrocracking of the Fischer-Tropsch (FT) product was investigated using the Pt-loaded zeolite catalysts at 250 °C with an initial H2 pressure of 0.5 MPa, and reaction time of 1 h. The Pt catalyst with a Pt particle size of 4.2 nm prepared using the microemulsion exhibited the maximum corresponding jet fuel yield (30.0%), which was higher than that of the impregnated catalyst.

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Hydroisomerization and hydrocracking of n-heptane on Pth zeolites. Effect of the porosity and of the distribution of metallic and acid sites.

Cited by 212 publications

References 10 publications

Differences between MFI- and MEL-Type Zeolites in Paraffin Hydrocracking

Differences between MFI- and MEL-Type Zeolites in Paraffin Hydrocracking

Effect of the impregnation order on the nature of metal particles of bi-functional Pt/Pd-supported zeolite Beta materials and on their catalytic activity for the hydroisomerization of alkanes

Preparation for Pt-Loaded Zeolite Catalysts Using w/o Microemulsion and Their Hydrocracking Behaviors on Fischer-Tropsch Product

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